Farm Forestry New Zealand

Prepare grass sites by spot spraying a one metre circle for each planting site. Use glyphosate herbicide with spray dye a few days before planting as this will not leave chemical residue in the soil. Prepare spots using straight lines and accurate spacings between spots so that trees can be easily found later. Cut down woody weeds and flatten these on the ground so they decay and don't support weed growth.

Take great care in the handling, transport and storage of seedlings, especially bare-rooted stock which must be kept cool and moist and planted as soon as possible after wrenching. Containerised (plug) stock should also be planted as soon as possible after receiving the plants. Make sure the root plugs are moist by soaking in a water trough.

Plant trees with a slow release fertilizer tablet underneath or put a trowel of high nitrogen fertiliser such as DAP or urea in a spade slit above the seedling.

Do not "slit and stuff" bare-rooted plants. Plant as per these instructions ».

For containerised stock, dig a hole twice the size of the plant container, leaving some soft soil at the bottom. Tease out (straighten and trim) any pot-bound roots before firming the soil around them, ensuring there are no air cavities.

Remember:

• Prevent weeds from competing with the Kahikatea seedlings for at least three years after planting.
• Protect seedlings from browsing by stock and wild animals.

Ensure the newly planted tree gets enough light, moisture and nutrients to establish unimpeded. Maintain young trees by clearing or spraying weeds around them for at least two years or until they are well established and growing. Seek advice on choice of chemical if release spraying.

Native trees, being slower growing than exotics, may require releasing from weeds for several years so they don't become smothered by early weed competition.

During establishment Kahikatea responds to side shade by growing faster, straighter and taller with fewer branches. A nurse species that grows fast initially but does not grow too big, such as manuka, can be planted to provide side shelter. The nurse crop should ideally be planted a year or two ahead of the Kahikatea.

Overhead shade slows down growth. For good growth rates release trees from competing vegetation so some direct sunlight always reaches the tree’s leader. Climbing plants and dense woody weeds can overtop young native trees and may require manually cutting back to provide a light-well for the young tree to grow up through.

Where Kahikatea regenerates with manuka and gorse it will overtop these species within two or three decades, sooner if provided sufficient light.

Clearwood pruning: The aim of clearwood pruning is to minimise the defect core and produce wood free of knots. Pruning "lifts" must be regular and undertaken at a frequency that minimises branch size and diameter over stubs (DOS). Ideally, only final crop trees would be clear-pruned. The smaller more horizontal branches on lower stems of Kahikatea established within a highly-stocked stand (i.e. 1600 stems per hectare or more) will generally self-prune when they are shaded out. Larger, upward pointing branches should be removed as soon as possible as they will reduce height growth and increase defect core diameter.

Clearwood pruning guidelines are available here.

Suitable pruning tools include loppers and a pruning hand-saw, a battery-operated reciprocating saw, or battery-operated loppers. Form pruning can be undertaken by using a pole pruner.

Close spacings provide better height growth and small branches but with a reduced diameter growth rate. Thinning is required to reduce stocking (number of trees per hectare) and encourage diameter growth in residual "crop" trees.

Harvesting of Kahikatea is controlled by the Forests Act (and must be undertaken sustainably). Planted Kahikatea may be harvested for timber without controls if the owner has obtained a certificate from the Ministry for Primary Industries. The process is described here. 

Timber return on investment

No published calculations show return on investment for growing Kahikatea for commercial purposes. Although a simple calculation suggests earnings from carbon credits might overtake the costs of establishment after 20 years, this calculation is sensitive to every assumption and no claim is made that it is true or accurate. The assumptions used were:

• Establishing 400 stems per ha at $5 per stem ($2,000 per ha)
• Cost of capital 5% pa real
• Lookup tables for indigenous forests apply: price of carbon $30 per NZU real 
• Excluding the costs of land, rates, management and ETS compliance.

Carbon sequestration rate over time, and relevant Look-up Tables

If the land is registered under the Emissions Trading Scheme and the trees are planted so as to comply, i.e. at least one hectare, with tree crown cover of more than 30 percent in each hectare and an average width of tree crown cover of at least 30 metres, then they should earn carbon credits. The relevant look-up tables for determining how quickly they store carbon and earn credits, and guides to how to use the tables, may be downloaded here.

As Kahikatea is an indigenous softwood, tables A2.2 and A2.4 apply, suggesting that over its first 30 years Kahikatea stores carbon at a rate of approximately one third as fast as radiata pine.

Outside the ETS this carbon calculator suggests how much carbon a planted native forest will store over time.